Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JPH1056684 [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker device for sound reproduction. [0002] 2. Description of the Related Art Various types of loudspeakers can be considered and put to practical use as loudspeakers for sound reproduction. [0003] For example, a magnetic circuit having a gap between the center pole portion of the first magnetic yoke and the plate is formed by sandwiching the magnet by the first magnetic yoke called pole piece and the second magnetic yoke called plate. A speaker unit in which the primary coil is fixed in the air gap of the magnetic circuit and fixed to the diaphragm so as to face it, and the secondary coil is disposed in the air gap of the magnetic circuit; It has been put to practical use. [0004] In this electromagnetically coupled speaker, the secondary current is induced in the secondary coil by the signal current flowing through the primary coil, and the secondary coil is driven according to the secondary current by the interaction with the magnetic flux generated in the air gap of the magnetic circuit. A force is generated to vibrate the diaphragm to which the secondary coil is fixed. 11-05-2019 1 [0005] In this electromagnetically coupled speaker, the primary coil through which the signal current flows is fixed to the first and / or second magnetic yokes made of a magnetic material such as iron, so that it has the advantage of excellent heat dissipation and being able to withstand large inputs. There is. In addition, if the secondary coil is formed of a nonmagnetic conductive material such as aluminum, and a short coil formed of a pipe or a cylinder forming a one-turn coil, distortion can be reduced. [0006] On the other hand, a conductive type speaker in which a voice coil is disposed in the air gap of the magnetic circuit has been put to practical use, and in this conductive type speaker, power is supplied to the voice coil and unnecessary vibration is caused in the vibration system including the voice coil. In order not to apply resistance, the voice coil is joined to a terminal provided on the speaker frame by a lead wire made of a tinsel wire. [0007] In addition, the voice coil is divided into bits of digital audio signal by this conductive speaker, and each coil is directly driven by data of each bit corresponding to each bit of digital audio signal. Is considered. [0008] As described above, the electromagnetically coupled speaker has the advantages of being excellent in heat dissipation and being able to withstand a large input, and also capable of reducing distortion. However, when the length of the air gap of the magnetic circuit is increased, the sensitivity of the speaker is reduced, so the number of turns of the primary coil and the secondary coil can not be increased. 11-05-2019 2 [0009] Therefore, the inductance of the primary coil and the secondary coil can not be increased, and the electromagnetic coupling force in which the secondary current is induced in the secondary coil by the signal current flowing in the primary coil is as low as several kHz to 1 kHz or less It becomes smaller in the region, and it is impossible to play up to 20 Hz, which is necessary for playing audio. Therefore, the electromagnetic coupling speaker is mainly used only as a speaker for highpitched sound reproduction. [0010] On the other hand, as described above, in the conductive speaker, the voice coil is joined to the terminal provided on the speaker frame by the lead wire made of a tinsel wire. In addition, it has been considered to divide the voice coil into the number of bits of the digital audio signal and drive each coil directly with data of each bit of the digital audio signal using a conductive speaker. [0011] However, at present, when digitizing an audio signal, it is common to set the digital audio signal to 16 bits for faithful reproduction of the audio. Therefore, in the case of driving a voice coil with a digital audio signal in a conductive type speaker, 16 pairs of lead wires are required for one speaker. [0012] 11-05-2019 3 However, since the tinsel wires, which are the lead wires, largely shake with the vibration of the voice coil, the distance between them can not be reduced. Therefore, it is quite difficult to provide as many as 16 pairs of tinsel cords in a small speaker. [0013] Therefore, the inventor of the present invention has proposed a novel speaker device capable of reproducing up to the low frequency by driving the electromagnetic coupling speaker with a digital signal. [0014] FIG. 16 shows a cross-sectional view of a structure of an example of an electromagnetic coupling type speaker unit used for the novel speaker device. [0015] As shown in FIG. 16, the electromagnetic coupling type speaker unit of this example constitutes a first yoke 1 provided with a cylindrical center pole portion 1a and a disk shaped flange portion 1b, and a second yoke. A magnetic circuit is formed by a doughnut-shaped plate 2, a doughnutshaped magnet 3 disposed between the flange portion 1b of the first yoke 1 and the plate 2, and a magnetic gap GP between the plate 2 and the center pole portion 1a. Is configured. [0016] The flange portion 1b is provided with a magnet guide 15 having a step so that the center positions of the magnet 3 and the center pole portion 1a coincide with each other. Also, in assembling the magnetic circuit, a jig called a gap guide is used so that the center of the center pole portion 1a coincides with the center of the plate 2, and the size of the magnetic gap GP is equal to that of the center pole portion 21a. Between the outer circumferential surface of the plate 22 and the inner circumferential surface of the plate 22. [0017] 11-05-2019 4 Then, a drive coil as a primary coil is disposed on either or both of the outer peripheral surface portion of the center pole portion 1a and the inner peripheral surface portion of the plate 2 facing each other across the magnetic gap GP. In this embodiment, the primary coil 4 is disposed on the outer peripheral surface of the center pole portion 1a. In order to arrange the primary coil 4, a small diameter portion 1c having a length corresponding to the winding width of the primary coil 4 is provided in the vicinity of the top of the center pole portion 1a, and the primary coil 4 is provided on the small diameter portion 1c. Be [0018] In the case of this example, this primary coil 4 consists of a coil group of the number according to the bit number of the input digital signal. For example, in the case of a binary code in which the input digital signal is 16 bits / 1 sample and the most significant bit MSB is a sign bit (positive or negative), the primary coil 24 excludes the MSB corresponding to the number of bits. Fifteen coils are provided. [0019] And each of 15 coils is made into the number of turns according to the weight of each corresponding bit. When the digital audio signal is linearly quantized, the number of turns of the 15 coils changes in a geometric progression corresponding to each bit from the least significant bit LSB to the most significant bit MSB. It is assumed. For example, if the coil corresponding to the LSB is 2 turns, the coil corresponding to 15 SB is 4 turns, the coil corresponding to 14 SB is 8 turns, the coil corresponding to 13 SB is 16 turns, and so on. It will be increased. [0020] The lead wire pair 17 derived from the primary coil 4 (in fact, there are 15 pairs, but only one pair is shown in the figure for simplicity of explanation) is provided on the flange portion 1 b of the first magnetic yoke 1. The through hole 14 is extended to the back side of the flange portion 11-05-2019 5 1b. Then, each of the lead wire pairs 17 is connected to 15 input terminals 18 (only one input terminal is shown in the figure for simplicity of the description) provided on the back side of the flange portion 1 b. [0021] In this case, in order to dissipate heat from the lead wire pair 17, the lead wire pair 17 is bonded to the outer surface of the center pole portion 1 a and drawn out in the direction of the flange portion 1 b of the first magnetic yoke 1. [0022] Then, a secondary coil 5C formed of a short coil electromagnetically coupled to the primary coil 4 is inserted into the gap GP. In the case of this example, as shown in FIG. 17, the secondary coil units 5 constituting the secondary coil 5C are respectively nonmagnetic and conductive materials such as aluminum are formed in a cylindrical shape, It is considered to be a short coil of one turn. In this example, the coil bobbin is omitted, and the secondary coil unit 5 is configured by only the short coil 5C. Of course, a secondary coil unit can also be configured by winding a coil around a coil bobbin and shorting the both ends. [0023] The secondary coil unit 5 configured as described above is attached to the speaker frame 11 via the damper 10. In addition, a cone paper 9 as an example of a diaphragm is attached to and attached to the secondary coil unit 5. The cone paper 9 is attached to the speaker frame 11 by the gasket 12 through the flexible edge 9 e. Finally, the cap 13 is adhesively attached to the top edge of the cone 9 or secondary coil unit 5. [0024] If signal input according to each bit of the digital signal is respectively added to the input terminals 18 of the number corresponding to the number of bits of the electromagnetically coupled speaker described above, the current flowing in each of the plurality of coils constituting the primary coil 4 Accordingly, a current is induced in the short coil as the secondary coil 5C, 11-05-2019 6 and the interaction with the magnetic flux in the air gap GP causes the secondary coil unit 5 to vibrate up and down according to Fleming's left-hand rule. [0025] In this case, the sampling frequency when digitizing the audio signal is a frequency such as 44.1 kHz or 48 kHz, which is twice as high as 20 kHz which is said to be the upper limit of the audio frequency. Therefore, low frequency components such as several kHz to 1 kHz or less of the voice signal before being digitized are also high frequencies exceeding 20 kHz as the digital voice signal. [0026] In addition, the electromagnetic coupling speaker reduces the length of the air gap of the magnetic circuit so that the speaker sensitivity does not decrease, and the signal flowing in the primary coil even if the number of turns of the primary coil and the secondary coil is reduced. When the frequency of the current is such a high frequency that exceeds 20 kHz, the electromagnetic coupling force does not decrease, and sound can be reproduced. [0027] Then, in the speaker device of the present invention configured as described above, since the primary coil of the electromagnetic coupling speaker is driven by the digital audio signal, the low frequency component of the audio signal before being digitized is also The signal current flowing through the primary coil has a high frequency exceeding 20 kHz. Therefore, the electromagnetic coupling speaker enables reproduction up to the low frequency range. [0028] Like general speakers, the vibration system of the speaker unit is not sensitive to high 11-05-2019 7 frequencies, and in particular, hardly reproduces high frequency components such as 20 kHz or more. Therefore, even if the plurality of coils of the primary coil are driven by the digital signal of the sampling frequency of 44.1 kHz or 48 kHz, the sampling frequency component is hardly reproduced. Even if the sound is reproduced with a very small sound pressure, sounds over 20 kHz can hardly be heard by the human ear, so no problems occur even when listening to music. [0029] In addition, it is also easy to intentionally form a mechanical filter having a stop band of 20 kHz or more and incorporate it into the speaker unit. [0030] In addition, it is possible to realize a speaker apparatus with small distortion and a large maximum output, which reproduces the audio directly by the digital audio signal without using the D / A converter and the power amplifier. [0031] By the way, in this electromagnetic coupling speaker, mid-high range sound is emitted from the central portion of the cone paper 9 and the portion of the cap 13. For this reason, the secondary coil unit 5 and the cone paper 9 and the cap 13 need to be firmly adhered and fixed in order to vibrate in the middle and high regions. [0032] However, since the cone paper 9 and the cap 13 and aluminum, which is the secondary coil unit, are bonded by an adhesive such as an epoxy agent, the strength is weak compared to the integrated product, and hence the middle and high frequency characteristics are There is a possibility that the sound quality of the mid-high range may deteriorate. [0033] In view of the above, the present invention has an object to provide a speaker apparatus using the above-described novel electromagnetically coupled speaker unit, which can improve the middle to high band characteristics and the middle to high band sound quality. Do. 11-05-2019 8 [0034] SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, a primary coil fixed in the vicinity of an air gap in a magnetic circuit, and the primary coil disposed in the air gap, It is attached to a secondary coil composed of a short coil in which a secondary current is induced according to the current flowing in the coil, and a coil bobbin of a secondary coil unit in which the secondary coil is formed, and a speaker via an edge portion A speaker unit comprising a main diaphragm fixed to a frame and an auxiliary diaphragm attached to the secondary coil as an integral part, and a speaker drive circuit for driving the primary coil of the speaker unit by a digital audio signal And [0035] The secondary coil has a cylindrical shape made of a nonmagnetic material and a conductive material, and the coil bobbin is omitted to constitute a secondary coil unit, and the subdiaphragm is integrated with the cylindrical secondary coil. It is good to form as a part. [0036] According to this invention of the above configuration, the sound of the middle and high frequencies is reproduced by the sub diaphragm formed as an integral part of the secondary coil unit. Therefore, the middle to high frequency characteristic is improved, and the sound quality of the middle to high frequency becomes good. [0037] BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a speaker device according to the present invention will be described below with reference to the drawings. [0038] FIG. 1 shows a cross-sectional view of a structure of an embodiment of a speaker unit used for a speaker device according to the present invention. [0039] 11-05-2019 9 As shown in FIG. 1, the speaker unit of this example is an electromagnetically coupled speaker, and the structure of the portion of the secondary coil unit is different from that of the speaker unit of the example of FIG. Is almost the same. [0040] That is, in the speaker unit of this example, the first yoke 21 including the cylindrical center pole portion 21a and the disk-shaped flange portion 21b, the toroidal plate 22 constituting the second yoke, and A magnetic circuit is constituted by a doughnut-shaped magnet 23 disposed between the flange portion 21 b of the yoke 21 and the plate 22 and a magnetic gap GP between the plate 22 and the center pole portion 21 a. [0041] The flange portion 21b is provided with a magnet guide 35 having a step so that the center positions of the magnet 23 and the center pole portion 21a coincide with each other. [0042] Then, a drive coil as a primary coil is disposed on either or both of the outer peripheral surface portion of the center pole portion 21a and the inner peripheral surface portion of the plate 22 facing each other across the magnetic gap GP. In this embodiment, the primary coil 24 is disposed on the outer peripheral surface of the center pole portion 21a, as in the above-described example. In order to dispose the primary coil 24, a small diameter portion 21c having a length equivalent to the winding width of the primary coil 24 is provided in the vicinity of the top of the center pole portion 21a, and the primary coil 24 is fixed to the small diameter portion 21c. Be done. [0043] Also in this example, the primary coil 24 is composed of a coil group whose number corresponds to the number of bits of the input digital signal, and as described above, for example, the input digital signal is 16 bits / 1 sample, and the highest order In the case of a 2'-complement code in which the bit MSB is a sign bit (positive or negative), for example, 15 coils are provided as the primary coil 24 corresponding to the number of bits. 11-05-2019 10 [0044] And each of 15 coils is made into the number of turns according to the weight of each corresponding bit. When the digital audio signal is linearly quantized, the number of turns of the 15 coils changes in a geometric progression corresponding to each bit from the least significant bit LSB to the most significant bit MSB. It is assumed. [0045] When the analog voice signal is nonlinearly quantized and converted to a digital voice signal, the number of turns of the plurality of coils constituting the primary coil 24 changes in the geometric progression as described above. Instead of changing it, it should be changed according to the non-linear characteristic of the non-linear quantization. [0046] An example of the primary coil 24 is shown in FIG. 2A. This example is a case where the primary coil 24 is configured as an air core coil. That is, as shown in FIG. 2A, the primary coil 24 consists of 15 coils LA to LG, LI to LP each having a different number of turns, and from each coil LA to LG, LI to LP, the winding start and winding thereof The final lead pairs 37a-37g, 37i-37p are derived. Then, the primary coil 24 is inserted into the small diameter portion 21c of the center pole portion 21a shown in FIG. 2B, adhered, and fixed in the state as shown in FIG. [0047] The primary coil 24 may be a wire wound around a bobbin 36 of a magnetic material as shown 11-05-2019 11 in FIG. 3A, or as shown in FIG. 3B, the small diameter portion 21c of the center pole portion 21a. The wire may be directly wound and attached. [0048] Fifteen lead wire pairs 37a to 37p derived from the primary coil 24 pass through one or more through holes 34 provided in the flange portion 21b of the first magnetic yoke 21 to form the flange portion 21b. It is extended to the back side. Each of these lead wire pairs 37a to 37p (only one pair is described as a representative number 37 in FIG. 1) has 15 input terminals 38a to 38p (represented in FIG. 1) provided on the back side of the flange portion 21b. Only one is described as 38 as a number). [0049] In this case, the lead wire pairs 37a to 37p are bonded to the outer surface of the center pole portion 21a and dissipated in the direction of the flange portion 21b of the first magnetic yoke 21 for heat dissipation from the lead wire pairs 37a to 37p. Ru. As shown in FIG. 3B, instead of bonding, for example, paper 39 is wound from above the lead wire pair of the center pole portion 21a, and this paper 39 causes the lead wire pair to contact the center pole portion 21a side. You may make it press. [0050] And in this embodiment, the secondary coil 25C which consists of a short coil electromagnetically coupled with the primary coil 24 is inserted into the air gap GP. In the case of this example, the secondary coil 25C is formed as the secondary coil unit 25 itself. The secondary coil unit 25 may be configured by inserting a secondary coil consisting of a 11-05-2019 12 cylindrical ring into a coil bobbin, or by connecting both ends and shorting a coil by winding around the coil bobbin, but this embodiment In the same manner as in the above-described example, as shown in FIG. 4, a nonmagnetic and conductive material such as aluminum is cylindrically formed to form a one-turn short coil. By the coil 25C, the coil bobbin is omitted, and the secondary coil unit 25 is configured. [0051] Then, as shown in FIG. 4, the auxiliary diaphragm 26 is formed integrally with the secondary coil unit 25. The auxiliary diaphragm 26 is mainly for reproduction radiation of middle to high frequency sound, and has a shape of a sagger having a predetermined inclination. The integrated component 27 composed of the secondary coil unit 25 and the auxiliary diaphragm 26 forms, for example, a portion of the auxiliary diaphragm 26 by performing a processing process called shrinkage reduction on a cylindrical aluminum ring. It is molded by [0052] The auxiliary bobbin 28 or the secondary coil 25C is fixed and disposed on the outer peripheral portion of the secondary coil unit 25 above the magnetic gap GP of the integrated component 27 having the above-described configuration. Then, the auxiliary bobbin 28 or the secondary coil 25C is attached to the speaker frame 31 via the damper 30, so that the component 27 composed of the secondary coil unit 25 and the auxiliary diaphragm 26 is attached. [0053] In addition, cone paper 29 as an example of the main diaphragm is attached to the auxiliary bobbin 28 or the secondary coil 25C. The cone paper 29 is attached to the speaker frame 31 by the gasket 32 through the flexible edge 29e. 11-05-2019 13 [0054] For example, as shown in FIG. 5A, the auxiliary bobbin 28 is configured by winding a reinforcing paper 28P around a bobbin 28B in which rectangular plates are abutted and made annular. The inner diameter of the bobbin 28 B is set to be substantially equal to the outer diameter of the secondary coil unit 25. A state in which the predetermined position of the secondary coil unit of the component 27 is adhesively fixed to the auxiliary bobbin 28 in the example of FIG. [0055] In addition, as the auxiliary bobbin 28, one configured by a spiral bobbin 28S as shown in FIG. 5B can also be used. [0056] A method of assembling the speaker unit having the above configuration will be described below. [0057] As shown in FIG. 2B, the primary coil 24 is inserted into the portion of the small diameter portion 21c above the center pole portion 21a and adhered. [0058] Next, the lead wire pairs 37a to 37g and 37i to 37p from the 15 coils LA to LA, LI to LP constituting the primary coil 24 are pulled out to the back side of the yoke 21 through the through holes 34, and the input terminal Solder and fix to 38a-38g and 38i-38p. The lead wire portion in contact with the center pole portion 21a is bonded to the center pole portion 21a for the purpose of heat radiation. The above fixing of the primary coil 24 is performed in the process prior to the assembly of the magnetic circuit. 11-05-2019 14 [0059] Next, an adhesive is applied to the front surface of the flange portion 21b of the yoke 21 and the magnet 23 is placed, and the inner diameter of the magnet 23 and the outer diameter of the magnet guide 35 formed as a step on the front surface of the flange portion 21 The center pole portion 21a and the magnet 23 are aligned so that the centers of the center pole portion 21a and the magnet 23 substantially coincide with each other. [0060] Next, an adhesive is applied to the upper surface of the magnet 23 and the plate 22 is placed. Then, a jig called a gap guide is inserted so that the inner diameter of the plate 22 and the outer diameter of the center pole portion 21a are concentric. [0061] The speaker frame 31 is attached to the plate 22 in advance by means such as caulking. Alternatively, after completing the magnetic circuit, the speaker frame 31 may be attached to the plate 22 by means such as a screw. [0062] After the adhesive between the plate 22 and the magnet 23 is dried, the gap guide is pulled out of the center pole portion 21a. The body of the speaker is now complete. [0063] Next, a jig called an auxiliary bobbin 28 or a secondary coil 25C and a coil spacer is prepared. The coil spacer is a jig whose outer diameter is matched to the inner diameter of the auxiliary 11-05-2019 15 bobbin 28 or the secondary coil 25C, and whose inner diameter is matched to the outer diameter of the center pole portion 21a. [0064] Then, insert this coil spacer inside the auxiliary bobbin 28 or secondary coil 25C and align the coil spacer so that the auxiliary bobbin 28 or secondary coil 25C comes to a predetermined position above the gap GP. Insert it into the center pole 21a. [0065] Next, as it is, the outer peripheral part of the damper 30 is adhered to the speaker frame 31, and the inner peripheral part of the damper 30 is bonded and fixed to the outer peripheral part of the auxiliary bobbin 28, so that the secondary coil unit 25 has a center pole part. It is made to move freely in the axial direction of 21a. [0066] Next, the outer peripheral portion of the cone paper (main diaphragm) 29 with the edge 29 e is adhered and fixed to the outer peripheral portion of the speaker frame 31 via the gasket 32. Further, the inner peripheral portion of the cone paper 29 is adhered and fixed to the outer peripheral portion of the auxiliary bobbin 28 or the secondary coil 25C. Then, after the adhesive is dried, the coil spacer is pulled out from the center pole portion 21a. [0067] When the damper 30 and the cone paper 29 are attached to the secondary coil 25C, the cap 33 is adhered near the top of the auxiliary diaphragm 26, and the magnet 23 is magnetized to complete the speaker device. [0068] Next, the part of the secondary coil unit 25 of the integrated component 27 of the secondary coil 11-05-2019 16 unit 25 and the auxiliary diaphragm 26 shown in FIG. 4 is inserted into the inner peripheral side of the auxiliary bobbin 28, and the secondary coil After positioning so that 25C is at a predetermined position in the magnetic gap GP, adhesive fixing is performed. At this time, a coil spacer different from the above is prepared, and it is inserted between the secondary coil unit 25 and the center pole portion 21a. [0069] After the adhesive between the auxiliary bobbin 28 and the component 27 is dried, the coil spacer is pulled out of the center pole portion 21a. [0070] Then, the cap 33 is adhered in the vicinity of the top of the auxiliary diaphragm 26. After the adhesive is dried, the magnet 23 is magnetized to complete the speaker device. [0071] If a signal input corresponding to each bit of the digital signal is added to the input terminals 38a to 38g and 38i to 38p of the electromagnetic coupling type speaker unit described above, the secondary coil 25C is generated according to the current flowing through the primary coil 24. The current is induced, and the interaction with the magnetic flux in the air gap GP causes the secondary coil unit 25 to vibrate up and down according to Fleming's left-hand rule. In this case, the change period of the digital signal is 44.1 kHz or 48 kHz, which is its sampling frequency, and the inductive coupling force between the secondary coil 25C and the primary coil 24 does not decrease, and Reproduction is possible. [0072] Then, in the electromagnetic coupling type speaker unit of this example, the secondary coil 25C (secondary coil unit 25) is formed in a cylindrical shape of aluminum, and a sub-vibration plate 26 for middle and high sound is integrally provided therewith. Because of this, the Young's modulus of the junction between the secondary coil unit 25 and the auxiliary diaphragm 26 is 11-05-2019 17 very large compared to adhesion, and the rigidity is high, so that the deterioration of the midhigh frequency characteristics and the mid-high frequency sound quality is small. [0073] That is, there is a possibility that the mid-high frequency characteristic and the mid-high frequency sound quality may be deteriorated because the Young's modulus of the bonding portion between the cone paper 29 which is the main diaphragm and the secondary coil unit 25 is small. In the above, the presence of the auxiliary diaphragm 26 provided integrally with the secondary coil unit 25 improves the mid-to-high range characteristic and the sound quality of the mid-to-high range. [0074] Although the above-described embodiment is an example in which the secondary coil unit is constituted only by the secondary coil consisting of a cylindrical short coil, the cylindrical short coil is inserted in the bobbin or the short coil is wound in the bobbin It may be something. In that case, the secondary diaphragm is provided as an integral part with the bobbin of the secondary coil unit. [0075] In this specification, integral is not limited to the case of processing an integral body like a squeezer, but also welding, welding, etc. in which Young's modulus at a joint portion is 10 times or more larger than adhesion. It includes those which are joined and integrated by a joining method of the above into one part. [0076] Next, an example of an audio reproduction system using a speaker unit according to the present invention is shown in FIG. The example of FIG. 7 is a case where the voice is reproduced by the digital voice signal from the digital voice output device. 11-05-2019 18 [0077] The digital audio output device 210 is a CD player or DAT (digital audio tape recorder) or the like, from its digital output terminal, for example, from the left and right channel audio signals digitized to 16 bits at a sampling frequency of 44.1 kHz or 48 kHz. The stereo audio signal is output as serial data alternately for every one sample of left and right audio data. [0078] The 16-bit digital audio signal of serial data from the digital audio output device 210 is supplied to the serial-to-parallel converter 220, and the serial-to-parallel converter 220 separates the digital audio signals of the left and right channels. The 16-bit left and right digital audio signals converted into parallel data and converted into parallel data are supplied to the left and right channel speaker devices 100L and 100R. [0079] Although not shown, in the serial-to-parallel converter 220, a clock of a bit rate is obtained, and the clock of this bit rate is supplied to the decoder 70. [0080] The speaker devices 100L and 100R each include a decoder 70, a speaker drive circuit 40, and a speaker unit 110 in this example. The speaker unit 110 is configured of the electromagnetic coupling type speaker unit described using FIGS. 1 to 4 described above. [0081] Then, in the case of this example, in the speaker devices 100L and 100R, in the decoder 70, control signals as will be described later are generated from the 16-bit left and right digital audio signals converted to parallel data from the serial to parallel converter 220. The generated control signal is supplied to the speaker drive circuit 40, and the speaker drive circuit 40 drives the primary coil 24 of the speaker unit 110. 11-05-2019 19 [0082] When the primary coil 24 is composed of a plurality of coils, when the 16 bit digital audio signal is a 2 'complement code as shown in FIG. 8, its MSB (most significant bit) is used as a sign bit, As described above, and as shown in FIGS. 8 and 9, the primary coil 24 is composed of 15 coils LA to LG and LO to LP. Then, the coil LA is made to correspond to the LSB (least significant bit), for example, 2 turns, and the coils LB, LC, LD, LE, LF, LG, LI, LJ, LK, LL, LM, LN, LO, 4 LPs, 8 turns, 16 turns ... corresponding to 15SB, 14SB, 13SB, 12SB, 11SB, 10SB, 9SB, 8SB, 7SB, 6SB, 4SB, 3SB, 2SB, respectively. The number of turns is twice the number of turns of the coil corresponding to the three lower bits. [0083] When the analog voice signal is nonlinearly quantized and converted to a digital voice signal, the number of turns of the plurality of coils constituting the primary coil 24 changes in the geometric progression as described above. Instead, it changes according to the non-linear characteristic of the non-linear quantization. [0084] FIG. 10 shows an example of the part of the decoder 70 and the speaker drive circuit 40 shown in FIG. 7. The speaker drive circuit 40 corresponds to the 15 coils LA to LG and LI to LP of the primary coil 24. The coil drive circuits 40A to 40G and 40I to 40P are provided. [0085] In each of the coil drive circuits 40A to 40G and 40I to 40P, four FETs 51 to 54 as switching elements and corresponding ones of the coils LA to LG and LI to LP of the primary coil 24 are provided. A circuit configured by bridge connection and a constant current source 41 are connected in series. [0086] Then, when the FETs 51 and 53 are turned on and the FETs 52 and 54 are turned off, the current Ia of the constant current source 41 corresponds to a coil corresponding to each bit among the plurality of coils of the primary coil (hereinafter When the FETs 51 and 53 are turned off and the FETs 52 and 54 are turned on, the current Ia of the constant current source 41 is caused to flow 11-05-2019 20 in the negative direction to the corresponding primary coil. [0087] The currents of the constant current sources 41 of the coil drive circuits 40A to 40G and 40I to 40P are all made equal as indicated by the current Ia. In the same coil drive circuit, when all the FETs 51 to 54 are turned on or off, no current flows in the corresponding primary coil. [0088] The decoder 70 corresponds to the 15 coils LA to LG and LI to LP of the primary coil 24, that is, 15 control signal generation circuits 70A to 70G corresponding to 15 bits excluding the MSB of the digital audio signal. , 70I to 70P, and from the respective control signal generation circuits 70A to 70G and 70I to 70P, the MSBs of the digital audio signal converted into parallel data from the serial to parallel converter 220 and the respective control signal generation circuits 70A 70 control signals G1 to G4 to be described later are obtained respectively from lower bits (LSB to 2SB) corresponding to 70G and 70I to 70P, and the control signals G1 to G4 correspond to the speaker drive circuit 40. Are supplied to the gates of the FETs 51 to 54 of the coil drive circuit. [0089] The four control signals G1 to G4 are levels at which the control signals G1 and G3 turn on the FETs 51 and 53 when the MSB of the input digital audio signal is 0 and the corresponding lower bit is 1, and the control signals G2 and G4 are At the level at which the FETs 52 and 54 are turned off, the current Ia flows in the positive direction to the corresponding primary coil. On the other hand, when the MSB of the digital audio signal is 1 and the corresponding lower bit is 0, the control signals G1 and G3 turn off the FETs 51 and 53, and the control signals G2 and G4 turn on the FETs 52 and 54. A current Ia flows through the corresponding primary coil in the negative direction opposite to the above. [0090] 11-05-2019 21 Also, when the MSB of the digital audio signal is 0 and the corresponding lower bit is also 0, or when the MSB is 1 and the corresponding lower bit is also 1, the control signals G1 to G4 turn off the FETs 51 to 54. And no current flows in the corresponding primary coil. [0091] When all the control signals G1 to G4 turn on the FETs 51 to 54, it is possible to prevent current from flowing to the corresponding primary coil. In that case, a current always flows in the circuit, and a stable operation can be performed. [0092] The driving force F of the vibration system of the electromagnetic coupling speaker is the secondary current i induced in the secondary coil, the density B of the magnetic flux generated in the air gap of the magnetic circuit, and the length of the secondary coil in the air gap of the magnetic circuit Since the magnetic flux density B and the length L are constant as F = B · L · i as the product with L, the driving force F of the vibration system is the secondary current i induced in the secondary coil It will be proportional. The secondary current i induced in the secondary coil 25 is proportional to the product of the signal current flowing through the primary coil and the number of turns of the primary coil. [0093] Then, in the above-described example, the number of turns of each of the coils LA to LG and LI to LP of the primary coil 24 is set to the number of turns proportional to the weight of each bit excluding the MSB of the input digital audio signal. Among the 15 coils of the next coil 24, corresponding to the coil through which the current Ia flows as the signal current, the secondary coil 25C receives the primary coil 24 in the direction according to the value of the MSB of the digital audio signal. The secondary current of the current value proportional to the weight of the bit corresponding to the coil through which the current Ia flows is induced. [0094] 11-05-2019 22 That is, in the secondary coil 25C, a secondary current of the sum of current values proportional to the weight of the bit corresponding to the coil through which the current Ia of the primary coil 24 flows. Thereby, the cone paper 29, which is a diaphragm to which the secondary coil unit 25 is fixed, vibrates in the direction according to the value of the MSB of the input digital audio signal by an amount proportional to the digital data value of the one sample. The speaker unit 110 reproduces the audio faithful to the input digital audio signal. [0095] The switching elements of the coil driving circuits 40A to 40G and 40I to 40P are not limited to FETs, and other elements operating at high speed can be used. [0096] In the example described above, the number of turns of each of the coils LA to LG and LI to LP constituting the primary coil 24 is the number of turns proportional to the weight of each bit excluding the MSB of the input digital audio signal. In the case of reproducing the difference in weight of each bit of the audio signal, the number of turns of each of the coils LA to LG and LI to LP is the same, and the coil drive circuits 40A to 40G and 40I to 40P corresponding thereto are provided. By changing the current value of the constant current source, the difference in weight of each bit of the input digital audio signal can also be reproduced. [0097] FIG. 11 shows an example in this case, and the 15 coils LA to LG and LI to LP constituting the primary coil 24 are all made to have the same number of turns, for example, 50 turns, and the coils LA to LG, The currents Ia to Ig and Ii to Ip of the constant current sources 4LA to 41G and 41I to 41P of the coil drive circuits 40A to 40G and 40I to 40P corresponding to LI to LP are changed as described later. Others are the same as the example of FIG. 11-05-2019 23 [0098] As described above, the driving force F of the vibration system of the speaker unit 110 is proportional to the secondary current i induced in the secondary coil, and the secondary current i is the signal current flowing through the primary coil and the primary coil It is proportional to the product of the number of turns. [0099] Therefore, in this example, although not shown in FIG. 11, the current Ib of the constant current source of the coil drive circuit corresponding to the coil LB corresponding to 15SB of the digital audio signal as shown in FIGS. The current Ia of the constant current source 41A of the coil drive circuit 40A corresponding to the coil LA corresponding to the LSB of the digital audio signal is doubled. すなわち、Ib=2Iaとされる。 [0100] The currents Ic, Id, Ie,... Of the constant current source of the coil drive circuit corresponding to the coils LC, LD, LE... Corresponding to the digital audio signals 14SB, 13SB, 12SB,. , ... doubled. [0101] Therefore, as in the example of FIG. 10, in the speaker unit 110, the diaphragm 29 is proportional to the weight of the bit corresponding to the primary coil through which the signal current flows in the direction corresponding to the value of the MSB of the digital audio signal. It vibrates and the audio is reproduced faithfully to the input digital audio signal. [0102] When the difference in weight of each bit of the digital audio signal is reproduced by changing the current value of the constant current source as described above, one drive coil can be used as the primary coil. The primary coil in this case is attached to either the center pole portion 21 a or the plate 22. 11-05-2019 24 [0103] FIG. 12 shows an example in that case. However, this example is a case where the input digital audio signal, that is, the 16-bit digital audio signal converted into parallel data from the serial-to-parallel converter 220 is a natural binary code. [0104] In this example, the primary coil 111 is formed of one coil, and constant current sources 61A, 61B,... Of currents Ia, Ib,. , 61P are respectively connected via switch circuits 62A, 62B,..., 62P, and switch circuits 62A, 62B,..., 62P are switched by data of corresponding bits of the digital audio signal from serial to parallel converter 220. . [0105] That is, when a certain bit of the input digital audio signal is 1, the corresponding switch circuit is turned on, and the current of the corresponding constant current source flows through the primary coil 111. The current Ib of the constant current source 61B is twice as high as the current Ia of the constant current source 61A, and the current of the constant current source corresponding to each bit of the digital audio signal corresponds to one lower bit hereinafter. It is twice the current of the constant current source. [0106] Therefore, in this example, in the speaker unit 110, the diaphragm 29 vibrates in one direction by an amount proportional to the weight of each bit of the input digital audio signal, and the audio is reproduced faithfully to the input digital audio signal. [0107] 11-05-2019 25 The primary coil 111 is not one, and two or more coils having the same number of turns are provided, the current corresponding to each bit of 16 bits is divided into the corresponding number of groups, and the current of each group is one coil It can also be configured to flow against. For example, a primary coil is constituted by one coil provided in the center pole portion 21a and one coil provided in the plate 22, while the digital signal is divided into upper 8 bits and lower 8 bits. And a group of current corresponding to each of the two coils may be made to flow. [0108] Even when the input digital audio signal is a 2 'complement code, coil drive circuits 40A to 40P as shown in FIG. 11 are switched by data of corresponding bits of the digital audio signal. , And the primary coil 111 can be one. [0109] Furthermore, by combining the difference in the number of turns of the plurality of primary coils with the difference in the current value of the plurality of constant current sources, it is possible to reproduce the difference in weight of each bit of the digital audio signal. [0110] FIG. 13 shows an example in that case. However, this example is a case where the input digital audio signal, that is, the 16-bit digital audio signal converted into parallel data from the serial-to-parallel converter 220 is a natural binary code. [0111] In this example, the primary coil is composed of four coils 111S, 111T, 111U, and 111V with a turn ratio as described later, and drive blocks S, T, and T for the respective coils 111S, 111T, 111U, and 111V. U and V are provided, and constant current sources of currents Ia, Ib, Ic and Id respectively correspond to corresponding coils 111 S, 111 T, and 111 T via switching circuits. It 11-05-2019 26 is connected to 111U or 111V. [0112] That is, in drive block S, constant current sources 61A, 61B, 61C, 61D are connected to corresponding coils 111S via switch circuits 62A, 62B, 62C, 62D, respectively, and in drive block T, constant current source 61E. , 61F, 61G, 61H are connected to corresponding coils 111T via switch circuits 62E, 62F, 62G, 62H, respectively, and in the drive block U, constant current sources 61I, 61J, 61K, 61L are switch circuits respectively. 62I, 62J, 62K, and 62L are connected to the corresponding coil 111U, and in the drive block V, constant current sources 61M, 61N, 61O, and 61P are connected via switch circuits 62M, 62N, 62O, and 62P, respectively. The switch circuit 62A, 6 is configured to be connected to the corresponding coil 111V. B ... 62N, 62O, 62P is switched by the corresponding bit data of the input digital audio signal. [0113] The turn number ratio of the coils 111S, 111T, 111U and 111V is 1: 16: 162: 163. The ratio of the currents Ia, Ib, Ic, Id of the constant current sources 61A, 61B, 61C, 61D is 1: 2: 22: 23. すなわち、Ib=2・Ia,Ic=22 ・Ia,Id=23 ・Ia [0114] As described above, the driving force F of the vibration system of the speaker unit 110 is proportional to the secondary current i induced in the secondary coil, and the secondary current i is the signal current flowing through the primary coil. It is proportional to the product of the number of turns of the primary coil. [0115] Therefore, in this example, when a certain bit of the digital audio signal becomes 1, the corresponding ones of the switch circuits 62A, 62B... 62P are turned on, and the current flows to the primary coil 111S, 111T, 111U or 111V. With the flow of Ia, Ib, Ic or Id, the ratio of the secondary current induced in the secondary coil corresponds to the ratio of the weight of each bit of the digital audio signal. 11-05-2019 27 [0116] Therefore, as in the example of FIG. 12, in the speaker unit 110, the diaphragm 29 is shifted in one direction by an amount proportional to the weight of each bit of the digital audio signal, and the audio is reproduced faithfully to the input digital audio signal. Be done. [0117] And in this example, the ratio of the number of turns between the primary coil 111S of the minimum number of turns and the primary coil 111V of the maximum number of turns can be reduced to 1: 163 = 1: 212. In addition, the ratio of the current value between the minimum current value Ia and the maximum current value Id can be significantly reduced to 1:23. [0118] Although not shown, the primary coil is composed of four coils with a ratio of the number of turns of 1: 2: 4: 8, and the current value of each coil via the switch circuit is not shown. The four constant current sources with the ratio of 1: 16: 162: 163 are connected, and the combination of the four constant current sources with the smallest current value and each coil can be used as the LSB and 2SB of the input digital audio signal, respectively. , 3SB and 4SB corresponding to the input digital audio signals 5SB, 6SB, 7SB and 8SB, respectively, with the combination of four constant current sources with the second smallest current value and respective coils corresponding to The combinations of the four largest constant current sources and each coil correspond to the input digital audio signals 9SB, 10SB, 11SB and 12SB, respectively, and the four constant current sources having the largest current value and each coil set The combination may be made to correspond to the digital voice signals 13SB, 14SB, 15SB and MSB, respectively. According to this, between the minimum number of turns of the primary coil and the maximum number of turns of the primary coil The ratio of the number of turns of the current can be significantly reduced to 1: 8 and the ratio of the current value between the minimum current value to the maximum current value is significantly reduced to 1: 163. Can. [0119] In this way, it is possible to reproduce from bass to treble with flat frequency characteristics, and to reproduce audio directly from digital audio signals without using a D / A converter or a power amplifier. Low distortion, maximum output A large speaker device can be realized. [0120] 11-05-2019 28 FIG. 14 shows another example of the speaker device of the present invention. In this example, an analog audio signal Ao from an analog audio output device 510 such as a cassette player or an FM tuner is supplied to a chopper circuit 520, and an audio signal is audible in the chopper circuit 520 as shown by an analog audio signal Ac in FIG. It is chopped at a frequency fc higher than the frequency, that is, a frequency fc exceeding 20 kHz which is said to be the upper limit of the audio frequency. [0121] However, it is desirable that the chopping frequency fc be a high frequency around twice 20 kHz, for example, 40 kHz. In addition, the time width of the chopping period is sufficiently shorter than the chopping period Tc. [0122] Then, the chopped analog audio signal Ac from the chopper circuit 520 is amplified by the power amplifier 530 and supplied to the primary coil 111 of the speaker unit 110 described above. In this case, the speaker unit 110 has one primary coil 111. As a result of the audio signal current being supplied to the primary coil 111, a secondary current is induced in the secondary coil, and the diaphragm vibrates. [0123] As described above, the speaker unit 110, which is an electromagnetic coupling speaker, has a low frequency of several kilohertz to 1 kilohertz or less where the secondary current i is induced in the secondary coil by the signal current flowing through the primary coil 111. It becomes small. 11-05-2019 29 [0124] However, according to the example of FIG. 14, since the analog audio signal is interrupted at a frequency fc higher than the audio frequency and supplied to the primary coil 111 of the speaker unit 110, the low frequency component of the analog audio signal is also 1 The signal current flowing to the next coil 111 has a high frequency exceeding 20 kHz. Therefore, the frequency characteristic from the low band to the high band is flat by the speaker unit 110 which is an electromagnetic coupling speaker, and good reproduction of the sound quality becomes possible. [0125] As described above, according to the present invention, the sub-diaphragm for medium and high frequency range reproduction is integrally provided in the secondary coil unit of the electromagnetically coupled type speaker unit which is digitally driven. Improve the sound quality of middle and high range characteristics and middle and high range. [0126] Brief description of the drawings [0127] 1 is a cross-sectional view of the structure of an example of a speaker unit used in an embodiment of a speaker device according to the present invention. [0128] 2 is a diagram showing an example of a primary coil used in the speaker unit of FIG. [0129] 3 is a diagram showing another example of the primary coil used in the speaker unit of FIG. [0130] 11-05-2019 30 4 is a diagram showing an example of an integrated component of the secondary coil and the auxiliary diaphragm used in the speaker unit of FIG. [0131] 5 is a diagram showing an example of the auxiliary bobbin used in the speaker unit of FIG. [0132] 6 is a view showing a state in which the integrated component of FIG. 4 is attached to the auxiliary bobbin of the example of FIG. [0133] 7 is a diagram showing an example of an audio reproduction system using an example of the speaker device according to the present invention. [0134] 8 is a diagram for explaining the input digital signal. [0135] <Figure 9> It is the figure in order to explain the drive principle of the speaker device due to this invention. [0136] 10 is a circuit diagram showing a specific example of a partial circuit of FIG. [0137] <Figure 11> It is the figure which shows one example of the audio playback system which uses the other example of the speaker device due to this invention. [0138] 12 is a diagram showing an example of an audio reproduction system using another example of the speaker apparatus according to the present invention. 11-05-2019 31 [0139] 13 is a diagram showing an example of an audio reproduction system using another example of the speaker device according to the present invention. [0140] 14 is a diagram showing an example of an audio reproduction system using another example of the speaker device according to the present invention. [0141] 15 is a diagram for explaining the example of FIG. [0142] 16 is a cross-sectional view of the structure of the conventional speaker device. [0143] 17 is a diagram showing an example of the secondary coil unit of the conventional speaker apparatus of FIG. [0144] Explanation of sign [0145] 21: first magnetic yoke, 21a: center pole portion, 21b: flange portion, 22: second magnetic yoke (plate), 23: magnet, 24: drive coil (primary coil), 25: secondary coil DESCRIPTION OF SYMBOLS 26 ... Auxiliary diaphragm, 27 ... Integrated component, 28 ... Auxiliary coil, 29 ... Cone paper as an example of a main diaphragm, 29e ... Edge, 30 ... Damper, 31 ... Speaker frame, 32 ... Gasket, 33 ... Cap, 34 through hole 35 magnetic guide 37a to 37g and 37i to 37p lead wire pair 38a to 38g and 38i to 38p input terminal GP: magnetic gap 11-05-2019 32
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